2-Chloropropionaldehyde can find applications as useful intermediates for chemicals, agricultural chemicals and medicines. It has been known to produce this compound from vinyl chloride, carbon monoxide and hydrogen as raw materials, as disclosed, for example, in French Patent No. 1,397,779 and HELVETICA CHIMICA ACTA, 48(5), 1151-1157. All of these processes employ cobalt carbonyl as a catalyst In French Patent No. 1,397,779 referred to above, for example, the raw materials are reacted for 90 minutes under the conditions of a reaction temperature of 110.degree. C. and a reaction pressure of 200 atm., thereby obtaining reaction results of a vinyl chloride conversion of 57.4% and a selectivity to 2-chloropropionaldehyde of 86.2%
However, these processes which employ cobalt carbonyl as a catalyst require cobalt carbonyl in a large amount and a reaction pressure as high as 160-200 atm. because the catalytic activity per unit amount of cobalt is extremely low. Moreover, the reaction is carried out at a reaction temperature of 75.degree.-125.degree. C. for 90-120 minutes.
The intended product, 2-chloropropionaldehyde, is a thermally-unstable material. Under the conditions of such a reaction temperature and reaction time, a substantial portion of 2-chloropropionaldehyde is consumed through a consecutive reaction and the reaction yield is thus reduced. Accordingly, these processes have poor reproducibility.
Further, hydrogen chloride is by-produced through the consecutive reaction or other side reactions. It causes the materials of reactor to suffer severe corrosion and it reacts with the cobalt carbonyl catalyst to form cobalt chloride. Therefore, the processes involve problems of developing an obstacle to the reutilization of the catalyst.
In these processes, no reference is made to the separation of the product, 2-chloropropionaldehyde, from a reaction solution containing the catalyst or to the recovery and recycle of the catalyst which is important in the industrial production of 2-chloropropionaldehyde.